Oil companies have been under considerable pressure to ensure that environmental concerns are given priority in the planning and installation of petrol station infrastructures. This has not been without significant on-cost. One important advancement has been the use of pipeline systems constructed from plastics materials which have enabled the oil companies to install cost-effective environmentally acceptable alternatives to steel pipework systems which tend to corrode over time.
However, over recent years there have been major developments in fuel technology which have culminated in commercially available alternative fuels containing additives which have replaced lead-based antiknock compounds. Research continues to center on reducing sulphur content and hazardous emissions from fuel. In order to eliminate lead and sulphur from fuels, exotic additives and octane enhancers such as MTBE (methyl tertiary butyl ether) have been developed which are based on complex organic or heavy metal organic additives.
The presence of these additives in fuel can give rise to major environmental issues. Some such issues are described in an article entitled “MBTE—How should Europe Respond”, in Petroleum Review February 2000 pages 37-38. The entire text of this article is incorporated herein by reference by way of background information. The authors conclude that lead and some other metals are the most effective octane enhancers. However, lead is in the final stages of being phased out because of environmental and health issues, and the most readily available alternative, MMT (methylcyclopentadienyl manganese tricarbonile) is currently not widely accepted. The only other octane enhancers currently available are MTBE and other ethers such as ethyl tertiary butyl ether (ETBE) and tertiary amyl methyl ether (TAME), or alcohols such as ethanol. The ethers all tend to have similar properties and drawbacks. Ethanol is already used as a gasoline-blending component in parts of the United States where it is readily available, and in Brazil. It is an effective octane booster but has a number of drawbacks: it needs a “water-free” distribution system and is not without ground water issues. It is not recommended by the motor industry and is not cost-competitive.
To further complicate matters, the State of California has recently taken a decision to phase out MTBE. This decision was made not on health grounds but because of the taste and odor impact it can have on ground water in the event of an accidental spill. This presents a real dilemma for the oil companies because no short-term alternative appears to be acceptable to all parties.
The principal public concern is the contamination of ground water, particularly where it is used for drinking water supplies. Small amounts of MTBE are able to taint large volumes of water. A single spirit measure (30 ml) in a large swimming pool (500 m3) is around the taste and odor threshold.
MTBE is used throughout Europe to boost octane rating in fuels, especially in super unleaded and lead-replacement grades. It will be used in increased amounts because the new EU fuels legislation which came into effect on 1 Jan. 2000 requires that benzene, aromatics and olefins contents of gasoline fall to lower levels and that leaded gasoline is phased out.
MTBE is a volatile, water-soluble, oxygen-containing, colorless liquid with an ethereal odor. Although is has been added to gasoline for some years, public awareness over its use emerged when reformulated gasoline became mandatory over large areas of the US in a bid to reduce vehicle exhaust emissions of carbon monoxide. MTBE has since been found in drinking water supplies and in ground water wells. This, together with the contamination of Lake Tahoe (a drinking water resource) by unburned 2-stroke fuel from boats and jet-ski exhausts, led the governor of California to call for the phasing out of MTBE use. These concerns have been largely supported by a Blue Ribbon Panel set up by the US Environmental Protection Agency (EPA).
The introduction of new fuel mixtures and esoteric additives has led oil companies to question whether existing pipeline systems can cope with the new fuels with regards to mechanical performance and permeability resistance. If either of these issues were found to be a problem at some time in the future then the oil companies would like the option to remove and replace existing pipework systems with the minimum of cost and effort. The current methods of removing such pipework are costly and disruptive and generally would involve major excavations and thus disruption to forecourt trading operations.
At the same time there is the ongoing issue of monitoring and collecting any gaseous fractions that may be emitted from such pipeline systems, particularly if new fuel mixtures are found to effect pipeline materials. This monitoring is particularly important where the additives used are water-soluble. In the event of a major spill these additives would almost inevitably enter the petrol interceptor system which is mandatory on forecourt installations. However, because the MTBE class of additives are water-soluble they will simply pass through the interceptor and enter the local drainage system.
It is an object of the present invention to provide a containment, vapor extraction and leak detection systems which overcome or at least mitigate some or all of the problems outlined above.